U.S. Pat. Nos. 4,773,485, 4,834,188 and 5,127,479, each assigned to the assignee of the present invention, disclose systems for extinguishing fires which occur on residential cook stoves, fryers and ranges. While the systems disclosed in these patents have gained wide acceptance and function effectively to extinguish fires on residential cook stoves and ranges and fryers, these patents rely on an array of heat sensing elements coupled to one another with cables strung around the internal periphery of range hoods. Since these systems require at least some skill in mechanical assembly and require adjustments in cable length, they are systems which are somewhat difficult for the average home owner to install. Moreover, these systems are relatively expensive.
Attempts have been made to develop electronic systems which do not have the difficulties of cable systems. U.S. Pat. 4,830,116 and 4,887,674 are exemplary of such systems but the systems disclosed in these patents have not been commercialized. An impediment to the installation of electronic systems is their apparent complexity and utilization of house current as a source of electric power for the systems.
Other electronic systems are exemplified by U.S. Pat. Nos. 5,186,260 and 5,207,276; however, these systems rely on twisted insulated conductors which limit an alarm signal upon the insulation melting which is an irreversible system subject to degradation over time.
In addition, prior art arrangements are not easy to install and require drilling, measuring, screwing and bolting which procedures tend to discourage their installation.
In view of the aforementioned considerations, there is a need for a fire extinguishing system, suitable for commercial and residential cook stoves, fryers and ranges, as well as other heating and heated devices, which is very easy to install and is less expensive than the aforementioned, prior art systems as well as the electronic systems proposed in the patent literature.